ONSTED — Fewer than 40 students at Onsted Community Schools could be affected by a state mandate that prohibits unvaccinated students from attending classes following a recent report of several cases of chickenpox.

A letter from the Lenawee County Health Department sent out Thursday says any student who was not protected against chickenpox or who had not already had the illness would be prohibited from attending school for 21 days. However, a revised letter sent out later Thursday said those students could return as soon as Dec. 12, said Superintendent Mark Haag.

The health department can make such a mandate through the Michigan Public Health Code. Students who receive the first of two vaccines and schedule the second dose could return to school sooner than Dec. 12.

Haag said the district sent out communications Friday to approximately 40 students who could be affected by the mandate. Haag said he expects some or most will provide proof of having been vaccinated or having already had chickenpox.

“We still won’t know the impact until Monday,” he said.

Haag said school nurse Laura Dowling informed him earlier this week about the chickenpox cases at the school — numbering less than 10 — and contacted the health department as a matter of procedure.

Haag said the immunization compliance per building is 97 to 100 percent and that the students reporting chickenpox at this time are at the elementary and middle school buildings.

Those who do not get vaccinations tend to do so out of personal or religious convictions, the superintendent said.

In the meantime, Haag said the district remains concerned about providing educational support to those students who may be forced to stay home from school.

“This is a new situation for all of us,” Haag said of the mandate. He said those who are affected should keep in contact with the building principals and teachers to help affected students stay current with their studies.